Minimizing Power Consumption in Age of Information Constrained Cell-Free Massive Mimo Networks

Upcoming 6G networks are expected to serve several mission-critical cyber-physical systems (CPS) applications that demand timely and fresh control updates. Different from traditional quality of service (QoS) metrics, Age of Information (AoI) measures the freshness of information for CPS applications. To efficiently serve such applications, cell-free massive multipleinput multiple-output (CF-mMIMO) has emerged as a better alternative to traditional cellular architectures. To the best of our knowledge, the time-average power minimization problem has not been addressed so far in AoI-constrained CF-mMIMO networks. In this context, we aim to minimize the time-average power consumed in CF-mMIMO networks with maximum tolerable average AoI constraints, along with communication QoS and per-transmitter power budget constraints. We propose a novel iterative scheduling and precoding algorithm to achieve our objective. Detailed analytical modeling and resulting simulation illustrate the performance of our algorithm as a function of a penalty parameter, which show the average AoI of all users are within constraint limits. We also show that the penalty parameter allows to dynamically prioritize between the time-averages of power consumed and AoI as per performance requirements.